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Ga-doped ZnO 투명전극을 적용한 교류무기전계발광소자 특성 연구
이운호,장원태,김종수,이상남 한국반도체디스플레이기술학회 2017 반도체디스플레이기술학회지 Vol.16 No.2
We explain optical and electrical properties of top and bottom-emission structured alternating-current powder electroluminescent devices (ACPELDs) with Ga-doped ZnO(GZO) transparent electrode. The top-emission ACPELDs were layered as the metal electrode/dielectric layer/emission layer/top transparent electrode and the bottom-emission ACPELDs were structured as the bottom transparent electrode/emission layer/dielectric layer/metal electrode. The yellow-emitting ZnS:Mn, Cu phosphor and the barium titanate dielectric layers were layered through the screen printing method. The GZO transparent electrode was deposited by the sputtering, its sheet resistivity is 275 Ω/□. The transparency at the yellow EL peak was 98 % for GZO. Regardless of EL structures, EL spectra of ACPELDs were exponentially increased with increasing voltages and they were linearly increased with increasing frequencies. It suggests that the EL mechanism was attributed to the impact ionization by charges injected from the interface between emitting phosphor layer and the transparent electrode. The top-emission structure obtained higher EL intensity than the bottom-structure. In addition, charge densities for sinusoidal applied voltages were measured through Sawyer-Tower method.
적색 Sr2Si5N8:Eu2+ 형광체의 발광 파장 제어에 대한 연구
이운호,박광원,장원태,강태욱,이상남 한국화상학회 2016 한국화상학회지 Vol.22 No.2
Eu2+ 이온이 도핑된 질화물 형광체 Sr2Si5N8:Eu2+는 탄소열 환원 질화법 (Carbothermal Reduction Nitridation, CRN)을 이용하여 제조된다. X-선 회절분석기를 이용하여 구조를 관찰할 수 있다. 흡수 밴드 피크인 470 nm 는 Photoluminescence Exitation (PLE) 측정을 통해 확인할 수 있다. 이러한 여기 광은 InGaN 기반으로 한 발광다이오 드에 적용시키기에 효과적일 것으로 기대되며, (Sr1-xEux)2Si5N8:Eu2+ 형광체는 Eu2+ 이온 도핑 농도에 따라 628 nm 부터 670 nm 까지의 피크 파장을 얻을 수 있다. Eu2+의 농도가 증가할수록 발광 파장이 길어지는 적색 편이 현상을 관찰할 수 있다. 청색 발광다이오드에 Y3Al5O12:Ce3+ 형광체와 함께 적용하여 우수한 연색성을 갖는 백색광을 얻을 수 있었다. Eu2+-doped nitride phosphor, Sr2Si5N8:Eu2+, was prepared by the carbothermal reduction and nitridation method. Lattice structure is observed by the X-Ray diffractometer. Absorption band peaking at 470 nm is observed by the photoluminescence exitation measurement. The Sr2Si5N8:Eu2+ phosphor is excited at blue lights in the range of 450 - 470 nm that matches with the InGaN-LEDs. The emission peak position of (Sr1-xEux)2Si5N8 phosphor obtained from 628 to 670 nm with increasing Eu2+ ion concentartion. (Sr1-xEux)2Si5N8 phosphor apply to the blue LED with Y3Al5O12:Ce3+ phosphor which obtained white light of high color rendreing index.